Can’t you stamp the dang ballots with a barcode or something so someone can say ‘gee something changed on 20,000 ballots since the first time through’ ... ?
That is a good idea ... the barcode would be a hash value computed from the actual places that were marked on each ballot. In a recount the ballot reading machine would calculate the hash value again in the same manner and compare that answer to the bar code value. If the values don’t agree, spit the ballot out to a different stack.
Good idea. However this system could be defeated by placing a label over the bar code or some other means that destroys the original information. The law may have to be changed to allow nullification and destruction (or quarantine) of those ballots.